Electronic and electrical products are increasingly applied in people's lives; impact of an electronic and electrical product on another electronic and electrical product during operation needs to be considered. In addition, attention needs to be further paid to impact of electromagnetic radiation on human health. Electromagnetic radiation specifications and requirements for electronic and electrical devices have become one of market access standards of countries and regions. At present, EMI of an entire system is controlled mainly in two manners, so that electromagnetic wave energy radiated by the entire system to the outside is suppressed.
The first manner is, after hardware design of a board is completed, a metal shielding enclosure is customized, so as to form a Faraday cage to improve performance of controlling EMI of the entire system. However, costs of customizing a metal Faraday cage is high; in addition, to achieve a better shielding effect, a small quantity of holes are disposed in the Faraday cage, which affects heat dissipation of the board.
The second manner is, a customized wave-absorbing material is used to shield and attenuate a radiation source of a board. However, in existing design, an installation area on a surface of the radiation source and around the radiation source is limited. The wave-absorbing material needs to provide very strong wave-absorbing performance, which also results in high costs of the wave-absorbing material.